1. Field of the Invention
The present invention relates to a conductive material with a laminated structure, and more particularly to a conductive material with a laminated structure, where conductive particles are dispersed on the surfaces.
2. Description of the Prior Art
Spherical conductive particles are generally used for providing electrical conductance between the terminals of the glass substrate and the driving component of a conventional liquid crystal display, as shown in FIG. 1A to FIG. 1C. A conductive material 3 is coated on or adhered to the surface of the glass substrate 1, on which terminals 2 are formed. Then, the surface of the driving component 4, on which terminals 5 are formed, is joined to the surface of the glass substrate 1, on which terminals 2 are formed, in a manner of terminal-to-terminal alignment by the conductive material 3. Electrical conductance occurs between the terminals 2 and 5 in Z direction; electrical insulation occurs at the direction of X-Y plane.
The conductive material 3 is formed of a thermoplastic layer or a thermosetting layer, where spherical conductive particles 31 are evenly dispersed, as shown in FIG. 2A. However, it is necessary to apply external electrical and magnetic fields on the conductive material 3 to evenly distribute the conductive particles 31 in the conductive material 3 to prevent the conductive particles 31 from clustering. It is also necessary to use equipment to control accuracy. The manufacturing cost is thus increased.
Moreover, when the terminal 5 of the driving component 4 is press jointed to the terminal 2 of the glass substrate 1 of the liquid crystal display by the conductive material 3, electrical conductance in Z direction between the terminals 2 and 5 is established via the conductive particles 31, as shown in FIG. 2B. Because the conductive particles 31 are squeezed between the glass substrate 1 and the driving component 4, a short circuit may occur among the conductive particles 31 outside the joining region of the terminals 2 and 5. That is, an un-expected electrical conductance at the direction of X-Y plane is established, as shown in part A of FIG. 2B.
With the increasing requirement for higher resolution and for smaller size in connection with a liquid crystal display, it is necessary to have a shorter pitch between the terminal 2 of the glass substrate 1 and the terminal 5 of the driving component 4. As a result, junction impedance between the terminals 2 and 5 would be increased due to the reduction of the joining area. To satisfy the requirement for fine pitch, the size of the conductive particles 31 needs to be reduced. As a result, the level of difficulty in fabricating the conductive particles 31 and the manufacturing cost are increased. Besides, the surface roughness of the terminals 2 and 5 also limits the development of small-size conductive particles 31. When the size of the conductive particles 31 is smaller than what the surface roughness of the terminals 2 and 5, may permit bad electrical conductance would occur. When the density of the conductive particles 31 is increased, the requirement for joining with fine pitch cannot be attained, although the junction impedance can be reduced. Owing to the above considerations, the conventional conductive material is applied for joining in case of pitches larger than 50 microns.
Accordingly, it is desirable to provide a conductive material, which can overcome the above drawbacks and is suitable for fine-pitch joining between the terminals of the liquid crystal display and the driving component.